Concernsof Hericide resistant Gene Transfer - Herbicide Resistance Genes

A second concern in the areaof gene transfer deals with herbicide resistant genes being encoded into cropsand then being unintentionally transferred to weed species. Worldwide, 50million hectares are planted with genetically modified crops, an area equal tothe size of Germany. ("Biotech Goes Wild" TechnologyReview , July/August 1999) Two-thirds of these crops are engineered to beherbicide resistant. One third of the soybeans grown in the United States areRoundup Ready soybeans.("Biotech Goes Wild" TechnologyReview , July/August 1999)

The advantage of creatingherbicide resistant crops is that a farmer can spray weedkiller all over afield, destroying the weeds, but not harming the crops at all. But there isgreat concern about an unintended side effect of creating herbicide resistantcrops. The genes for herbicide resistance could be transferred from crops toweedy relatives of those crops. The result would be a weed resistant toherbicide, and conceivably flourishing out of control. Even worse, is thepossibility of "superweeds," pests that have picked up geneticresistance to several herbicides from genetically modified crops.( TheRoyal Society , September 3 1998)

Initially, scientists believedanti-herbicide genes would not flow from crops to weeds because crop-weed hybridplants, which would carry the genes, would die out because hybrids do not tendto flourish. ( NewScientist , 15 August 1998) But there is much recent evidence to suggest thatherbicide-resistant genes can be transferred from genetically engineered cropsto other plants.

For example, in 1998researches studied genetically modified mustard plants. This species of mustardtypically self-pollinates, so it was assumed that there was little chance of theplant's genes being transferred to another organism. The researches then plantedthe normal variety of this mustard plant, a version genetically modified to beresistant to herbicides, and a naturally occurring version of the mustard plantthat had herbicide resistance. The surprising results were that the geneticallyengineered plants were 20 times more likely to transfer their genes to otherplants than the naturally occurring resistant plants were. ("Biotech GoesWild" TechnologyReview , July/August 1999) .Earlier in 1996, Danish scientists noted that thegenetically engineered Brassica napus was breeding with its weedy relativeBrassica campestris. The result of this breeding were plants that looked likeBrassica campestris but were herbicide resistant like Brassica napus had beenengineered to be.("Biotech Goes Wild" Technology Review , July/August 1999)